Herxheimer reactions are situations in which a chronic infection patient, usually with a spirochete infection such as lyme disease, have a temporary worsening of their symptoms after initiating antimicrobial treatment. This could be with antibiotics or herbs. These are not drug side effects, like the common nausea, or diarrhea, but rather a worsening of the original symptoms such as joint pain or swelling. In joint pain and stiffness, it is obvious and easy to see the intensification of symptoms, but this can also occur in the mental health realm.
Some patients may complain of simply impaired cognition or "brain fog" - and this can markedly worsen as well. But depressive symptoms, anxiety and panic symptoms are also very common. Such "emotional" or "mental" herxes can go with time, and sometimes can also be managed and treated well with symptomatic treatment such as prescription medications or herbal options as well. Importantly, the central nervous system can become "hypersensitive" and amplify both pain signals as well as have an inability to filter to stimulation - ie. light and sounds become painful.
Such herxheimer reactions are usually temporary, lasting about a week, and then some degree is improvement is seen until the next reaction occurs, which is often at the 4 week point. These monthly cycles can often be seen in lyme as the bacteria has a life cycle in which it increases its growth rate at certain times.
Useful measures for emotional / mental herxheimer reactions include drugs such as antidepressants, tricyclics especially for pain, modafinil for "brain fog", quercetin and theracumin for pain / inflammation, lavender and passionflower for anxiety.